The present application claims priority to Japanese Applications No. P11-294515 filed Oct. 15, 1999, which application is incorporated herein by reference to the extent permitted by law.
1. Field of the Invention
This invention relates to an inspection apparatus used in inspecting a semiconductor wafer carrying a pre-set device pattern thereon.
2. Description of Related Art
A semiconductor device is fabricated by forming a fine device pattern on a semiconductor wafer. When forming such device pattern, it is a frequent occurrence that contaminants be affixed to the semiconductor wafer to produce grazing and resultant defects. The semiconductor wafer, suffering these flaws, prove a reject to lower the production yield.
That is, in order to stabilize the yield of a production line at a high level, it is desirable to locate the defects produced by contaminants or scratches to locate the cause to take effective measures on a production equipment or on a production process.
So, if a defect is located, an inspection apparatus is used to check the type of the defect for classification to identify the equipment or process responsible for the defect. The inspection apparatus for checking into the defect type is like an optical microscope and views the defect to an enlarged scale to identify the defect.
Meanwhile, if contaminants are affixed to the semiconductor wafer being inspected, proper inspection cannot be executed. So, the inspection of a semiconductor wafer needs to be executed in a clean environment.
For maintaining a clean environment in which to carry out semiconductor wafer inspection, such a method is effective in which a main body portion of the inspection apparatus be covered by a clean box and in which the interior of the clean box be kept to a high degree of cleanliness. If, in such case, the semiconductor wafer to be inspected is transported in a hermetically sealed vessel and the semiconductor wafer is moved by this vessel into the clean box, it is possible to prevent the contaminants effectively from being affixed to the semiconductor wafer to carry out the inspection of the semiconductor wafer properly without the necessity of maintaining the entire environment for the inspection apparatus at a high degree of cleanliness.
Meanwhile, the device pattern of a semiconductor wafer to be inspected is becoming finer with progress in improving the integration degree of the semiconductor device, such that recently the design rule is as fine is 0.18 xcexcm or less. In inspecting this fine pattern, contaminants of extremely small size, which raised no serious problems in the past, now may be a factor obstructing proper inspection. It is therefore necessary to maintain the environment of inspection at a higher degree of cleanliness, in order to carry out proper inspection of the fine device pattern, such that, if extremely small contaminants are produced in the course of the inspection, these may be effectively prevented from being affixed to the semiconductor wafer.
It is therefore an object of the present invention to provide an inspection apparatus whereby a highly clean environment is realized to enable proper inspection of a fine device pattern.
The present inventors have conducted eager searches for accomplishing the above object, and have found that, by supplying clean air into the clean box and by properly controlling the stream of the clean air supplied into this clean box, it is possible to prevent contaminants such as fine dust effectively from becoming affixed to the article being inspected to achieve the inspection of fine patterns satisfactorily.
According to the present invention, there is provided an inspection apparatus including a main body portion for inspecting an article for inspection, a clean box for accommodating the main body portion therein and an air supplying unit for furnishing clean air into the inside of the clean box, in which the main body portion is provided with an inspection stage for setting the article for inspection thereon and a cassette accommodation portion for carrying therein a cassette in which the article for inspection is loaded, and in which there are provided opening areas in at least portions of a lateral surface of the clean box located laterally of the inspection stage and the cassette accommodation portion for allowing clean air supplied from the air supplying unit into the inside of the clean box to be passed over the inspection stage 14 and through the cassette loaded in the cassette accommodation portion so as to be discharged to outside the clean box.
In the inspection apparatus according to the present invention, the interior of the clean box in which to hold the main body portion of the apparatus is kept in a clean environment by clean air supplied thereto from the air supply unit. In this inspection apparatus, there are provided opening areas in at least portions of the lateral sides of the clean box lying laterally of the inspection stage and the cassette accommodating portion provided in the main body portion, so that the clean air supplied from the air supply unit to the inside of the clean box is passed through the inspection stage carrying the article to be inspected and through the cassette housed in the cassette accommodating portion so as to be discharged to outside the clean box. This effectively prevents contaminants produced in the clean box from becoming attached to the article for inspection mounted on the inspection stage or to the article for inspection loaded in the cassette accommodating portion to enable the article to be inspected properly by the main body portion.
Preferably, the clean box is provided with a jutting portion at approximately the same height level as the lower, end of the inspection stage. The jutting portion is protruded towards the main body portion. By providing the jutting portion at approximately the same height level as the lower end of the inspection stage, the clean air supplied from the air supplying unit into the clean box can be routed properly over the inspection stage.
Preferably, an inclined guide portion for routing clean air supplied from the air supplying portion into the clean box into the cassette loaded in the cassette accommodating portion is provided in the vicinity of the cassette accommodating portion in the main body portion. By providing the inclined guide portion in the vicinity of the cassette accommodating portion in the clean box, the clean air supplied from the air supplying unit into the clean box can be routed properly into the cassette.
Also preferably, an inspection stage on which the article for inspection is set is provided in the main body portion, whilst there is provided a partitioning wall section between the inspection stage and the cassette accommodating portion for partitioning the inspection stage and the area of the cassette accommodating portion from each other. By providing the partitioning wall section between the inspection stage and the cassette accommodating portion, it is possible to prevent contaminants such as dust produced in the area of the inspection stage from intruding into the area of the cassette accommodating portion to prevent the contaminants from becoming attached to the article loaded in the cassette.
In the inspection apparatus according to the present invention, there are provided opening areas in at least portions of the lateral sides of the clean box lying laterally of the inspection stag and the cassette accommodating portion provided in the main body portion, so that the clean air supplied from the air supply unit to the inside of the clean box is passed through the inspection stage carrying the article to be inspected and through the cassette housed in the cassette accommodating portion so as to be discharged to outside the clean box. This effectively prevents contaminants produced in the clean box from becoming attached to the article for inspection mounted on the inspection stage or to the article for inspection loaded in the cassette accommodating portion to enable the article to be inspected properly by the main body portion.